Maintaining SL connection for sidelink (SL) configured with discontinuous reception (DRX)

Abstract

Certain aspects provide a method for wireless communication by a first user equipment (UE). The method generally includes monitoring signaling from the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE, determining whether the first UE and the second UE are within communication range based on the monitoring, and taking one or more actions based on the determination.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 17 / 165,528, filed on February 2, 2021, which claims the benefit of and priority to U.S. Provisional Application No. 62 / 983,122, filed on February 28, 2020, both of which are hereby assigned to the assignee of the present application and are hereby expressly incorporated by reference in their entireties, as if fully set forth below, and for all applicable purposes. Technical Field

[0003] Aspects of the present disclosure relate to wireless communications, and more particularly to techniques for sidelink communications. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, etc. These wireless communication systems may employ multiple access technologies that are capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, Advanced LTE (LTE-A) systems, Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and the like.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, or even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR aims to better support mobile broadband Internet access by improving spectral efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefixes (CP) on downlink (DL) and uplink (UL). To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0006] However, as the demand for mobile broadband access continues to increase, further improvements to NR and LTE technologies are needed. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that adopt these technologies. Summary of the invention

[0007] The systems, methods, and devices of the present invention each have several aspects, no single aspect of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the claims that follow, certain features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description of the Invention," it will be understood how the features of the present disclosure provide advantages including improved sidelink communication techniques.

[0008] Certain aspects provide a method for wireless communication by a first user equipment (UE). The method generally includes monitoring signaling from a discontinuous reception (DRX) configuration of at least one of the first UE or a second UE during a DRX cycle associated with a DRX configuration of the second UE, determining whether the first UE and the second UE are within communication range based on the monitoring, and taking one or more actions based on the determination.

[0009] Certain aspects provide a method for wireless communication by a first UE. The method generally includes generating signaling to be used to determine whether the first UE and a second UE are within communication range, and sending the signaling to the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE.

[0010] Certain aspects provide an apparatus for wireless communication by a first UE. The apparatus generally includes a memory and one or more processors coupled to the memory, the one or more processors and the memory being configured to: monitor signaling from the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE; determine whether the first UE and the second UE are within communication range based on the monitoring; and take one or more actions based on the determination.

[0011] Certain aspects provide an apparatus for wireless communication by a first UE. The apparatus generally includes a memory and one or more processors coupled to the memory, the one or more processors and the memory being configured to: generate signaling to be used to determine whether the first UE and a second UE are within communication range; and send the signaling to the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE.

[0012] Certain aspects provide an apparatus for wireless communication by a first UE. The apparatus generally includes means for monitoring signaling from a second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or a second UE, means for determining whether the first UE and the second UE are within communication range based on the monitoring, and means for taking one or more actions based on the determination.

[0013] Certain aspects provide an apparatus for wireless communication by a first UE. The apparatus generally includes means for generating signaling to be used to determine whether the first UE and a second UE are within communication range, and means for sending the signaling to the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE.

[0014] Certain aspects provide a computer-readable medium having instructions stored thereon that cause a first UE to monitor signaling from a second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or a second UE, determine whether the first UE and the second UE are within communication range based on the monitoring, and take one or more actions based on the determination.

[0015] Certain aspects provide a computer-readable medium having instructions stored thereon that cause a first UE to generate signaling to be used to determine whether the first UE and a second UE are within communication range, and to send the signaling to the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE.

[0016] To accomplish the above and related ends, one or more aspects include the features fully described and particularly pointed out in the following claims. The following description and drawings set forth in detail certain illustrative features of one or more aspects. However, these features are only indicative of several of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to be able to understand the above-mentioned features of the present disclosure in detail, a more specific description briefly summarized above may be made by reference to various aspects, some of which are shown in the accompanying drawings. However, it should be noted that the attached drawings only illustrate certain typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the description may allow for other equally effective aspects.

[0018] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0019] Figure 2 is a block diagram conceptually illustrating designs of example base stations (BSs) and user equipment (UEs) in accordance with certain aspects of the present disclosure.

[0020] Figure 3A and Figure 3B A pictorial representation of an example vehicle-to-everything (V2X) system is shown in accordance with certain aspects of the present disclosure.

[0021] Figure 4A

[0013] In certain aspects, example discontinuous reception (DRX) configurations for a UE are illustrated.

[0022] Figure 4B A keep-alive period in accordance with certain aspects of the present disclosure is shown.

[0023] Figure 5 is a flow diagram illustrating example operations for wireless communications in accordance with certain aspects of the present disclosure.

[0024] Figure 6 is a flow diagram illustrating example operations for wireless communications in accordance with certain aspects of the present disclosure.

[0025] Fig. 7A , Figure 7B and Figure 7C Transmission of keep-alive signaling between UEs in accordance with certain aspects of the present disclosure is illustrated.

[0026] Figure 8 A communications device is shown that may include various components configured to perform operations of the techniques disclosed herein.

[0027] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation. DETAILED DESCRIPTION

[0028] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for determining whether a user equipment (UE) is within range of another UE for sidelink (SL) communication. One or more UEs may operate in a discontinuous reception (DRX) mode of operation. Keep alive signaling may be periodically sent by a transmitting UE (Tx UE). A receiver UE (Rx UE) may receive the keep alive signaling and determine whether the Tx UE is within communication range based on whether an energy level associated with the signaling is below a threshold.

[0029] The following description provides an example of a configuration for SL communication in a communication system and does not limit the scope, applicability, or examples set forth in the claims. The functions and arrangements of the elements discussed may be changed without departing from the scope of the present disclosure. Various examples may omit, replace, or add various processes or components as needed. For example, the described method may be performed in an order different from that described, and various steps may be added, omitted, or combined. Moreover, the features described with respect to certain examples may be combined in certain other examples. For example, any number of aspects described herein may be used to implement a device or practice a method. In addition, the scope of the present disclosure is intended to cover devices and methods practiced using other structures, functions, or structures and functions other than the various aspects disclosed herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of the claims. The word "exemplary" is used herein to mean "used as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be interpreted as being more preferred or advantageous than other aspects.

[0030] Generally, any number of wireless networks can be deployed in a given geographic area. Each wireless network can support a specific radio access technology (RAT) and can operate on one or more frequencies. RAT can also be referred to as radio technology, air interface, etc. Frequency can also be referred to as carrier, subcarrier, frequency channel, tone, subband, etc. Each frequency can support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, 5G NR RAT networks can be deployed.

[0031] Figure 1 An example wireless communication network 100 is shown in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a NR system (e.g., a 5G NR network).

[0032] like Figure 1 As shown, the wireless communication network 100 may include multiple base stations (BSs) 110a-z (each base station is also individually referred to as BS 110 herein, or collectively referred to as BS 110) and other network entities. BS 110 may provide communication coverage for a specific geographic area (sometimes referred to as a "cell"), which may be fixed or may move according to the location of the mobile BS 110. In some examples, BS 110 may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) in the wireless communication network 100 using any suitable transport network and through various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.). Figure 1In the example shown, BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more cells. BS 110 communicates with user equipment (UE) 120a-y (each UE is also referred to herein as UE 120 individually or collectively as UE 120) in wireless communication network 100. UE 120 (e.g., 120x, 120y, etc.) may be dispersed throughout wireless communication network 100, and each UE 120 may be fixed or mobile.

[0033] According to certain aspects, UE 120 may be configured to use a SL configured with discontinuous reception (DRX) to determine whether other UEs are within communication range. Figure 1 As shown, UE 120a includes a DRX manager 122. As described in greater detail herein, DRX manager 122 may be configured to send or receive keep-alive signaling.

[0034] The wireless communication network 100 may also include a relay station (e.g., relay station 110r), which is also referred to as a relay, etc., which receives data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and sends the data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relays transmissions between UEs 120 to facilitate communication between devices.

[0035] A network controller 130 may be coupled to a set of BSs 110 and may provide coordination and control for these BSs 110. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with each other (eg, directly or indirectly) via a wireless or wired backhaul.

[0036] Figure 2 BS 110a and UE 120a (eg, Figure 1 The present invention provides example components of the wireless communication network 100 of the present invention, which can be used to implement various aspects of the present disclosure.

[0037] At BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller / processor 240. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH), a group common PDCCH (GC PDCCH), etc. The data may be for a physical downlink shared channel (PDSCH), etc. The processor 220 may process (e.g., encode and symbol map) the data and the control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols such as a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a cell-specific reference signal (CRS). If applicable, a transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, and / or reference symbols, and may provide an output symbol stream to a modulator (MOD) 232a-232t. Each modulator 232 may process a corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may also process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The downlink signals from modulators 232a-232t may be transmitted via antennas 234a-234t, respectively.

[0038] At UE 120a, antennas 252a-252r can receive downlink signals from BS 110a and can provide received signals to demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 can adjust (e.g., filter, amplify, downconvert, and digitize) a corresponding received signal to obtain input samples. Each demodulator can also process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 can obtain received symbols from all demodulators 254a-254r, perform MIMO detection on the received symbols (if applicable), and provide detected symbols. Receive processor 258 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to data sink 260, and provide decoded control information to controller / processor 280.

[0039] On the uplink, at the UE 120a, a transmit processor 264 may receive and process data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 264 may also generate reference symbols for reference signals (e.g., for a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 (if applicable), further processed by demodulators 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signal from the UE 120a may be received by the antenna 234, processed by the modulator 232, detected by the MIMO detector 236 (if applicable), and further processed by the receive processor 238 to obtain decoded data and control information transmitted by the UE 120a. The receive processor 238 may provide decoded data to a data sink 239 and decoded control information to a controller / processor 240 .

[0040] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively.A scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0041] The controller / processor 280 and / or other processors and modules at the UE 120a may perform or direct the execution of processes for the techniques described herein. Figure 2 As shown, the controller / processor 280 of the UE 120a has a DRX manager 122. Although shown at the controller / processor, other components of the UE 120a may be used to perform the operations described herein.

[0042] Figure 3A and Figure 3B A diagrammatic representation of an example vehicle-to-everything (V2X) system is shown in accordance with certain aspects of the present disclosure. Figure 3A and Figure 3B The UE shown in FIG. 4 can communicate via a sidelink channel and can perform sidelink CSI reporting as described herein.

[0043] Figure 3A and Figure 3B The V2X system provided in provides two complementary transmission modes. Figure 3A The first transmission mode, shown by way of example in , involves direct communication between participants that are close to each other in a local area (e.g., also referred to as sidelink communication). Figure 3BThe second transmission mode shown by way of example in the figure relates to network communication through the network, which can be implemented through the Uu interface (e.g., a wireless communication interface between a radio access network (RAN) and a UE). As shown, UE 352, 354 can communicate with each other using a side link (SL) 398.

[0044] Reference Figure 3A , a V2X system 300 (e.g., including vehicle-to-vehicle (V2V) communications) is shown having two UEs 302, 304 (e.g., vehicles). A first transmission mode allows direct communication between different participants at a given geographic location. As shown, the vehicles can have a wireless communication link 306 with an individual (V2P) (e.g., via a UE) via a PC5 interface. Communications between UEs 302 and 304 can also occur via a PC5 interface 308. In a similar manner, communications can occur from UE 302 to other highway components (e.g., highway component 310), such as traffic signals or signs (V2I) via a PC5 interface 312. About Figure 3A For each communication link shown in , two-way communication can occur between elements, so each element can be a transmitter and receiver of information. The V2X system 300 can be a self-managed system that is implemented without assistance from a network entity. Since no network service interruption occurs during the switching operation of the moving vehicle, the self-managed system can achieve improved spectrum efficiency, reduced costs, and increased reliability. The V2X system can be configured to operate in a licensed or unlicensed spectrum, so any vehicle with an equipped system can access common frequencies and share information. This coordinated / common spectrum operation allows safe and reliable operation.

[0045] Figure 3B A V2X system 350 is shown for communicating between a UE 352 (e.g., a vehicle) and a UE 354 (e.g., a vehicle) through a network entity 356. These network communications may occur through discrete nodes, such as base stations (e.g., eNBs or gNBs), which send information to and receive information from (e.g., relay information between) the UEs 352, 354. Network communications through vehicle-to-network (V2N) links (e.g., Uu links 358 and 310) may be used, for example, for long-range communications between vehicles, such as for communicating the presence of a car accident some distance ahead along a road or highway. Other types of communications (such as traffic flow conditions, road hazard warnings, environmental / weather reports, and service station availability, etc.) may be sent by the nodes to the vehicles. Such data may be obtained from a cloud-based sharing service.

[0046] In some environments, two or more subordinate entities (e.g., UE) can use side link signals to communicate with each other. As described above, V2V and V2X communications are examples of communications that can be sent via side links. Other applications of side link communications may include public safety or service announcement communications, communications for proximity services, UE to network relay communications, device to device (D2D) communications, Internet of Everything (IoE) communications, Internet of Things (IoT) communications, mission-critical mesh communications, and other suitable applications. Generally speaking, a side link may refer to a direct link between a subordinate entity (e.g., UE1) and another subordinate entity (e.g., UE2). Therefore, a side link may be used to send and receive communications (also referred to herein as "side link signals") without relaying communications through a scheduling entity (e.g., BS), even if the scheduling entity may be used for scheduling or control purposes. In some examples, a licensed spectrum (unlike a wireless local area network, which typically uses an unlicensed spectrum) may be used to communicate side link signals.

[0047] Various sidelink channels may be used for sidelink communications, including a physical sidelink discovery channel (PSDCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), and a physical sidelink feedback channel (PSFCH). The PSDCH may carry discovery expressions that enable near-end devices to discover each other. The PSCCH may carry control signaling, such as sidelink resource configuration and other parameters for data transmission, and the PSSCH may carry data transmission. The PSFCH may carry feedback, such as channel state information (CSI) related to sidelink channel quality.

[0048] Example Techniques for Maintaining a Sidelink (SL) Connection with Discontinuous Reception (DRX)

[0049] In a discontinuous reception (DRX) mode of operation, the UE may enter a low power ("sleep") mode (also referred to herein as a "sleep phase"), which may also be referred to as a low power state, for a certain period of time (also referred to as a DRX off (OFF) period, phase, or duration), and wake up again during a DRX on (ON) (e.g., wake-up phase) period to check if there is any data to be received. The cycle of sleep and wake-up (DRX on and DRX off) periods repeats over time, allowing the UE to save power while maintaining communications.

[0050] Figure 4AAn example DRX configuration 400 for a UE is shown. As shown, the DRX configuration 400 may include DRX on phases 402, 404. As described herein, the DRX on phase is repeated for each DRX cycle. For example, as shown, the DRX on phase 402 is during a DRX cycle 406. The UE is awake during the DRX on phases 402, 404 to monitor signaling that may be received, and is in a low power state (e.g., a sleep phase) at other times (also referred to as a DRX sleep phase).

[0051] In certain scenarios, DRX configuration may be implemented for a UE in a sidelink (SL) communication. For example, a first SL UE may communicate with a second SL UE. Once the first SL UE enters the DRX on phase, the first SL UE may not know whether the second SL UE is still within the communication range. For a Uu link between a UE and a base station (BS) (e.g., a gNB), the BS is not mobile and sends out a synchronization signal block (SSB) so that the UE can detect that the BS is within the communication range (e.g., whether the UE is outside the range of the BS or whether the BS is outside the range of the UE). However, for SL communications between a first SL UE and a second SL UE, both UEs may be mobile and the SL UE may not send an SSB for detection by another SL UE. The SL UE may act similarly to a BS by sending out an SSB, but this may be expensive in terms of power consumption, processing power, and impact on performance. Certain aspects of the present disclosure provide techniques for SL UEs to determine whether other SL UEs are within the communication range when at least one UE is in a DRX operating mode. As described in more detail herein, determining whether a SL UE is within the communication range may be based on keep-alive signaling.

[0052] Figure 4B A keep alive period 412 according to certain aspects of the present disclosure is shown. The period associated with the keep alive period 412 may be longer than the period associated with the DRX cycle 406. As shown, during the keep alive period 412, there may be a keep alive opportunity 416 during which a keep alive signaling 414 may be sent by the TX UE. The keep alive signaling may be used by the RX UE to determine whether the RX UE and the TX UE are within communication range. For example, the RX UE may determine whether the energy level of the keep alive signaling 414 is above a threshold, based on which the RX UE determines whether the TX UE is within communication range.

[0053] Figure 5is a flow diagram illustrating example operations 500 for wireless communications in accordance with certain aspects of the present disclosure. Operations 500 may be performed, for example, by a first UE (eg, such as UE 120a in wireless communication network 100). The first UE with respect to operations 500 may be referred to as an Rx UE.

[0054] Operation 500 may be implemented as a processor on one or more processors (e.g., Figure 2 In addition, the UE may transmit and receive signals in operation 500, for example, through one or more antennas (e.g., Figure 2 In some aspects, the transmission and / or reception of signals by the UE may be implemented via a bus interface of one or more processors (eg, controller / processor 280) that obtain and / or output signals.

[0055] At block 505, operations 500 may begin with the first UE monitoring signaling (also referred to herein as a keep-alive signal or signaling) from a second UE (e.g., a Tx UE) during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE. In certain aspects, the signaling is monitored if the DRX configuration is configured for at least one of the first UE or the second UE.

[0056] At block 510, the first UE determines whether the first UE and the second UE are within communication range based on monitoring, and takes one or more actions based on the determination at block 515. For example, as described in more detail herein, if it is determined that the first UE and the second UE are out of range, the first UE may report to the BS.

[0057] In some aspects, the signaling is sent by the second UE during a plurality of periodic transmission opportunities. The first UE may select how often to monitor the signaling, based on which the signaling is monitored during one or more of the plurality of periodic transmission opportunities. For example, the selection of how often to monitor the signaling may be based on an energy level associated with receiving the signaling during one of the plurality of periodic transmission opportunities (e.g., a first or initial periodic transmission opportunity).

[0058] Figure 6 is a flow diagram illustrating example operations 600 for wireless communications in accordance with certain aspects of the present disclosure. Operations 600 may be performed, for example, by a first UE (eg, such as UE 120t in wireless communication network 100). The first UE with respect to operations 600 may be referred to as a Tx UE.

[0059] Operation 600 may be implemented as a processor on one or more processors (e.g., Figure 2In addition, the transmission and reception of signals by the first UE in operation 600 may be performed by one or more antennas (e.g., Figure 2 In some aspects, the transmission and / or reception of signals by the UE may be implemented via a bus interface of one or more processors (eg, controller / processor 280) that obtain and / or output signals.

[0060] At block 605, operations 600 may begin with the first UE generating signaling (also referred to as a keep-alive signal or signaling) to be used to determine whether the first UE and the second UE are within communication range. At block 610, the first UE may send signaling to the second UE during a DRX cycle associated with a DRX configuration of at least one of the first UE or the second UE.

[0061] In other words, the SL Tx UE periodically broadcasts (sends) a keep-alive signal in all directions. The (broadcast) time and frequency resources can be configured per SLTX-RX pair. If a TX UE communicates with more than one RX UE, a single keep-alive signal from the TX UE can be sent to all RX UEs. In addition, the keep-alive signal can be Tx-centric. In other words, as described in more detail herein, from the perspective of the Tx UE, the keep-alive signal can be unique, and the time and frequency resources used to send the keep-alive signal can be configured from the perspective of the Tx UE.

[0062] Fig. 7A , Figure 7B and Figure 7C 704 according to certain aspects of the present disclosure. In certain aspects, the time of the keep-alive signaling transmission can be configured independently of the DRX setting of the Tx UE. In other words, the time location of the keep-alive signaling can be configured independently of the DRX setting of the Tx UE (e.g., if the Tx UE is configured with DRX). During the time configured for the keep-alive signaling, both the TX UE and the RX UE must be awakened independently of the DRX setting of the TX / RX UE (e.g., if the TX or RX UE is configured with DRX). Fig. 7A As shown, keep-alive signaling may be sent during a keep-alive phase 402 .

[0063] During the time configured for sending the keep-alive signal, both the Tx UE and the Rx UE may have to wake up in order to receive the signaling regardless of whether the configured time falls into the DRX active time (sleep phase) of the Tx UE or the DRX active time of the Rx UE. Both the Tx UE 702 and the Rx UE 704 must wake up when the keep-alive signaling is sent. Since the period of the keep-alive signal is long, the impact of the UE having to wake up to send or receive the keep-alive signaling on the UE power consumption should be small. For example, depending on the UE mobility, the keep-alive signal may be sent every few seconds (e.g., 10 seconds).

[0064] A keep-alive signal may be a relatively light signal relative to the amount of information that the keep-alive signal is used to communicate and the frequency with which the keep-alive signal is sent. For example, a keep-alive signal may be lighter than an SSB because the keep-alive signal is sent less frequently and has less information (this is because, unlike an SSB, a keep-alive signal may not include system and timing information). In other words, an SSB may include information associated with a primary synchronization signal (PSS), a secondary synchronization signal (PSS), and a physical broadcast channel (PBCH), which may not be included in a keep-alive signal.

[0065] If the Rx UE 704 does not successfully receive the keep-alive signal from the Tx UE 702 (e.g., one or more times), the Rx UE 704 may conclude that the Tx UE 702 is out of range of the Rx UE 704. As used herein, if the energy level associated with the signaling detected by the Rx UE is below a threshold, the keep-alive signal is considered to have not been successfully received and indicates that the UE is out of range. For example, the Rx UE 704 may determine that the Tx UE 702 is not within the communication range, and may report to the BS via the Uu link that the Tx UE 702 is out of range. In response, the BS may take one or more actions to facilitate communication between the UEs. For example, the BS may add a relay for communication between the UEs, or act as a relay itself (e.g., as described with respect to Figure 3B described).

[0066] The Tx UE 702 may use a wide beam or a narrow beam to send a keep-alive signal. In some cases, the Tx UE may determine whether to use a wide beam or a narrow beam to send a keep-alive signal based on application type or configuration or location estimation (eg, location of the Tx UE and / or Rx UE).

[0067] Certain aspects relate to the periodicity of the transmission of the keep-alive signal. For example, from the perspective of the Tx UE, the transmission of the keep-alive signal can be based on a configured fixed base-period. In other words, the periodic transmission timing of the keep-alive signal can be based on a fixed periodicity. From the perspective of the Rx UE, the monitoring of the keep-alive signal can be adaptive. For example, the Rx UE can monitor the keep-alive signal during one or more base periods. If the Rx UE receives a first keep-alive signal from the Tx UE with high energy, the Rx UE can start monitoring the keep-alive signal with a lower frequency, and vice versa.

[0068] The keep-alive signal may include a known sequence for each SL Tx UE (e.g., known by the Tx UE and the Rx UE). For example, the keep-alive signal may be similar to a CSI-RS or a more generalized version of the CSI-RS. In some aspects, the keep-alive signal may be different from the CSI-RS sent by the BS on the Uu link. In the Uu link, the CSI-RS is used to determine channel state information. The channel state information can be used to determine the modulation and coding scheme (MCS). However, the keep-alive signal can be used to learn whether the channel quality is below or above a certain threshold. If the channel quality is below the threshold, the Rx UE can determine that the Tx UE is out of range. Therefore, the resource allocation for the keep-alive signal may not be as dense as the CSI-RS on the Uu link in both time and frequency. For example, the keep-alive signal may span only a portion of the bandwidth used by the CSI-RS and may be sent at a lower frequency than the periodicity at which the CSI-RS is usually sent. The sequence associated with the keep-alive signal may indicate an identifier (ID) of the Tx UE, thereby allowing the Rx UE to know which UE is sending the keep-alive signal.

[0069] In some aspects, due to the frequency selective SL channel, a wideband (e.g., 1 component carrier (CC) bandwidth (BW)) may be used to send the keep-alive signal. The frequency domain density may be lower than that of the CSI-RS. In other words, a portion of the BW of the channel may be used for certain SL communications, and if the keep-alive signal is not wideband (e.g., in a narrowband), it may not indicate whether the channel quality in the frequency band of interest for the communication is above a threshold.

[0070] As described herein, a keep-alive signal may include a known sequence that uniquely identifies a SL TX UE and may be used by the TX UE to send keep-alive signaling to all other UEs in communication with the TX UE. For a given SLUE pair (e.g., UE A and UE B), the two UEs may send keep-alive signals to each other, thereby allowing the two UEs to track whether the other party is within communication range. For example, at one moment, UE A may send a keep-alive signal to UE B, and at another moment, UE B may send a keep-alive signal to UE A. However, in some cases, the UE may forgo sending a keep-alive signal. For example, if Figure 7B As shown in FIG. 7 , the Rx UE 704 can detect that the Tx UE 702 is out of range based on the keep-alive signaling 706. If the Rx UE 704 is communicating only with the Tx UE 702, the Rx UE 704 does not send out further keep-alive signaling 708 to the Tx UE 702 (which is now the Rx UE with respect to the keep-alive signaling 708). In other words, the Rx UE 704 abandons sending the keep-alive signaling 708. However, as Figure 7C As shown, if Rx UE 704 also communicates with another Rx UE 710 (or one or more other UEs not shown) and at least one of Rx UE 704 or Rx UE 710 is configured with DRX, Rx UE 704 sends another keep-alive signaling regardless of whether Tx UE 702 is out of range.

[0071] Various aspects of the present disclosure have provided techniques for determining whether UEs in SL communication are within the range of each other when DRX configuration is applied. If DRX configuration is not applied, keep-alive signaling may not be sent because, in this case, the channel is closely and frequently monitored for channel state information (e.g., for MCS determination). In other words, if at least one of the two communicating UEs is configured with DRX, keep-alive signaling may be transmitted by the two communicating UEs. If neither of the two communicating UEs is configured with DRX, the UE does not transmit keep-alive signaling. For example, assume that UE1 communicates with UE2, UE3, and UE4. In addition, UE1 and UE2 are not configured with DRX, and UE3 and UE4 are configured with DRX. UE1 may send periodic keep-alive signaling during the configured time and frequency resources. Keep-alive signaling may reach UE2, UE3, UE4, but will be processed by UE3 and UE4 configured with DRX. If UE2 only communicates with UE1, UE2 may not send periodic keep-alive signaling. UE3 and UE4 may send periodic keep-alive signaling because they are configured with DRX.

[0072] Figure 8The diagram shows a method that may include operations configured to perform the techniques disclosed herein (such as Figure 5 and Figure 6 800 includes various components (e.g., corresponding to means plus function components) of the communication device 800 and the operations shown in FIG. 800 . The communication device 800 includes a processing system 802 coupled to a transceiver 808. The transceiver 808 is configured to send and receive signals for the communication device 800, such as the various signals described herein, via an antenna 810. The processing system 802 can be configured to perform processing functions of the communication device 800, including processing signals received and / or to be transmitted by the communication device 800.

[0073] The processing system 802 includes a processor 804 coupled to a computer readable medium / memory 812 via a bus 806. In some aspects, the computer readable medium / memory 812 is configured to store instructions (e.g., computer executable code) that, when executed by the processor 804, cause the processor 804 to perform Figure 5 and Figure 6 Operations shown. In some aspects, the computer-readable medium / memory 812 stores code 814 for application; code 816 for receiving / transmitting, code 818 for determining, code 820 for taking one or more actions (e.g., reporting), and code 821 for abandoning. In some aspects, the processor 804 has circuitry configured to implement the code stored in the computer-readable medium / memory 812. The processor 804 includes circuitry 822 for application; circuitry 824 for receiving / transmitting; circuitry 826 for determining; circuitry 828 for taking one or more actions (e.g., reporting); and circuitry 830 for abandoning.

[0074] Example aspects

[0075] Aspect 1. A method for wireless communication by a first user equipment (UE) includes: monitoring signaling from a second UE during a discontinuous reception (DRX) cycle associated with a DRX configuration of at least one of the first UE or the second UE, determining whether the first UE and the second UE are within a communication range based on the monitoring, and taking one or more actions based on the determination.

[0076] Aspect 2. The method according to aspect 1, wherein the one or more actions include: if the signaling is not successfully received, reporting to the base station that the first UE and the second UE are not within the communication range.

[0077] Aspect 3. The method according to aspect 2, wherein if the energy level associated with the signaling is below a threshold, the signaling is not successfully received.

[0078] Aspect 4. The method according to any one of Aspects 1 to 3, wherein the signaling is monitored if a DRX configuration is configured for at least one of the first UE or the second UE.

[0079] Aspect 5. A method according to any one of Aspects 1 to 4, wherein the signaling is sent by the second UE during multiple periodic sending opportunities, and the method also includes selecting a frequency for monitoring the signaling, and monitoring the signaling during one or more periodic sending opportunities among the multiple periodic sending opportunities based on the selection.

[0080] Aspect 6. The method of aspect 5, wherein the selection of the frequency of monitoring the signaling is based on an energy level associated with the reception of the signaling during one of the plurality of periodic transmission opportunities.

[0081] Aspect 7. A method according to any one of Aspects 1 to 6, wherein the signaling is sent during multiple periodic transmission opportunities, which occur less frequently than the transmission opportunities of synchronization signal blocks (SSBs) or channel state information (CSI)-reference signals (RS).

[0082] Aspect 8. The method according to any one of Aspects 1 to 7, wherein the signaling includes less information than SSB or CSI-RS.

[0083] Aspect 9. The method according to any one of Aspects 1 to 8 also includes: determining resources for sending other signaling, the other signaling is to be used by the second UE to determine whether the first UE and the second UE are within the communication range; and if the signaling from the second UE is not successfully received at the first UE, abandoning the sending of other signaling.

[0084] Aspect 10. A method according to any one of Aspects 1 to 9, wherein the signaling from the second UE is not successfully received at the first UE, the method further comprising: determining resources for sending other signaling; and sending other signaling if the first UE communicates with a third UE, the other signaling being used by the third UE to determine whether the first UE and the third UE are within the communication range.

[0085] Aspect 11. The method according to any one of aspects 1 to 10, wherein the signaling includes a sequence identifying the second UE.

[0086] Aspect 12. A method for wireless communication by a first user equipment (UE), comprising: generating signaling to be used to determine whether the first UE and a second UE are within communication range; and sending the signaling to the second UE during a discontinuous reception (DRX) cycle associated with a DRX configuration of at least one of the first UE or the second UE.

[0087] Aspect 13. The method according to aspect 12 further comprises determining whether to use wideband or narrowband to send signaling based on a configuration associated with the communication.

[0088] Aspect 14. The method according to any one of Aspects 12 to 13, further comprising determining whether to use a wide beam or a narrow beam to send signaling based on a configuration associated with the communication.

[0089] Aspect 15. The method according to aspect 14, wherein the configuration associated with the communication comprises at least one of an application type associated with the communication, or a location of the first UE or the second UE.

[0090] Aspect 16. The method according to any one of Aspects 12 to 15, wherein signaling is sent if DRX configuration is configured for at least one of the first UE or the second UE.

[0091] Aspect 17. The method according to any one of Aspects 12 to 16, wherein the signaling is sent during a plurality of transmission opportunities according to a configured periodicity.

[0092] Aspect 18. A method according to any one of Aspects 12 to 17, wherein the signaling is sent during multiple periodic transmission opportunities, which occur less frequently than the transmission opportunities of synchronization signal blocks (SSBs) or channel state information (CSI)-reference signals (RS).

[0093] Aspect 19. The method according to any one of Aspects 12 to 18, wherein the signaling includes less information than SSB or CSI-RS.

[0094] Aspect 20. The method according to any one of aspects 12 to 19, wherein the signaling includes identifying a sequence of the first UE.

[0095] Aspect 21. An apparatus comprising means for performing the method of any one of Aspects 1 to 20.

[0096] Aspect 22. An apparatus comprising at least one processor and a memory coupled to the at least one processor, the memory and the at least one processor being configured to perform the method of any one of Aspects 1 to 20.

[0097] Aspect 23. A computer-readable medium having stored thereon computer executable code for wireless communication, which, when executed by at least one processor, causes an apparatus to perform the method of any one of aspects 1 to 20.

[0098] The techniques described herein can be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology.

[0099] The techniques described herein can be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, although various aspects may be described herein using terms commonly associated with 3G, 4G and / or 5G wireless technologies, various aspects of the present disclosure may be applied to other communication systems based on generations.

[0100] In 3GPP, the term "cell" can refer to the coverage area of ​​a Node B (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term is used. In NR systems, the terms "cell" and BS, next-generation NodeB (gNB or gNodeB), access point (AP), distributed unit (DU), carrier or transmit receive point (TRP) can be used interchangeably. BSs can provide communication coverage for macro cells, pico cells, femto cells and / or other types of cells. Macro cells can cover a relatively large geographic area (e.g., a radius of several kilometers) and can allow unrestricted access to UEs with service subscriptions. Pico cells can cover relatively small geographic areas and can allow unrestricted access to UEs with service subscriptions. Femto cells can cover relatively small geographic areas (e.g., homes) and can allow limited access to UEs associated with femto cells (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.). BSs for macro cells can be called macro BSs. BSs for pico cells can be called pico BSs. BSs for femto cells can be called femto BSs or home BSs.

[0101] UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a customer premises equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a home appliance, a medical device or medical equipment, a biometric sensor / device, a wearable device (such as a smart watch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring, a smart bracelet, etc.)), an entertainment device (e.g., a music or video device, or a satellite radio, etc.), a vehicle-mounted component or sensor, a smart meter / sensor, an industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be considered machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node can, for example, provide a connection for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices, which can be narrowband IoT (NB-IoT) devices.

[0102] Some wireless networks (e.g., LTE) use orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as frequency tones, bins, etc. Each subcarrier can be modulated with data. Typically, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the spacing of the subcarriers can be 15kHz, and the minimum resource allocation (called a "resource block" (RB)) can be 12 subcarriers (or 180kHz). Therefore, the nominal fast Fourier transform (FFT) size can be equal to 128, 256, 512, 1024, or 2048 for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidth may also be divided into subbands. For example, a subband may cover 1.8 MHz (e.g., 6 RBs), and there may be 1, 2, 4, 8, or 16 subbands for a system bandwidth of 1.25, 2.5, 5, 10, or 20 MHz, respectively. In LTE, the basic transmission time interval (TTI) or packet duration is a 1 millisecond subframe.

[0103] NR can utilize OFDM with CP on both the uplink and downlink, and includes support for half-duplex operation using TDD. In NR, a subframe is still 1 millisecond, but the basic TTI is called a time slot. A subframe contains a variable number of time slots (e.g., 1, 2, 4, 8, 16, ... time slots) depending on the subcarrier spacing. NR RB is 12 consecutive frequency subcarriers. NR can support a basic subcarrier spacing of 15KHz, and other subcarrier spacings, such as 30KHz, 60KHz, 120KHz, 240KHz, etc., can be defined relative to the basic subcarrier spacing. Symbol and time slot lengths scale with subcarrier spacing. The CP length also depends on the subcarrier spacing. Beamforming can be supported, and the beam direction can be dynamically configured. MIMO transmission with precoding can also be supported. In some examples, the MIMO configuration in the DL can support up to 8 transmit antennas, with up to 8 streams and multi-layer DL transmission of up to 2 streams per UE. In some examples, multi-layer transmission of up to 2 streams per UE can be supported. Aggregation of multiple cells can support up to 8 serving cells.

[0104] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., BS) allocates resources for communications between some or all devices and equipment within its service area or cell. A scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources of one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. The base station is not the only entity that can be used as a scheduling entity. In some examples, a UE may be used as a scheduling entity, and resources may be scheduled for one or more subordinate entities (e.g., one or more other UEs), and other UEs may utilize resources scheduled by the UE for wireless communications. In some examples, a UE may be used as a scheduling entity in a peer-to-peer (P2P) network and / or a mesh network. In a mesh network example, UEs may communicate directly with each other in addition to communicating with a scheduling entity.

[0105] In some examples, two or more subordinate entities (e.g., UEs) can communicate with each other using side link signals. Real-world applications of such side link communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical meshing, and / or various other suitable applications. Generally speaking, a side link signal may refer to a signal that is sent from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, a licensed spectrum (unlike a wireless local area network, which typically uses an unlicensed spectrum) may be used to communicate side link signals.

[0106] The method disclosed herein includes one or more steps or actions for implementing the method. The method, steps and / or actions may be interchangeable with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0107] As used herein, a phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, ccc, or any other order of a, b, and c).

[0108] As used herein, the term "determine" includes a variety of actions. For example, "determine" may include calculating, estimating, processing, deriving, investigating, searching (e.g., searching in a table, a database, or another data structure), ascertaining, etc. Also, "determine" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. Also, "determine" may include resolving, selecting, deciding, establishing, etc.

[0109] The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but are given the full scope consistent with the language claims, unless specifically stated otherwise, where an element is cited in the singular form is not intended to mean "one and only one", but "one or more". Unless otherwise specifically stated, the term "some" refers to one or more. All structural and functional equivalents of the elements throughout the various aspects described in this disclosure that are known or will be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be included by the claims. In addition, nothing disclosed herein is intended to be donated to the public, regardless of whether such disclosure is explicitly stated in the claims. No claim element shall be interpreted according to the provisions of 35 U.S.C. § 112 (f) unless the element is explicitly stated using the phrase "a component for...", or in the case of a method claim, the element is stated using the phrase "a step for...".

[0110] The various operations of the above methods may be performed by any suitable components capable of performing the corresponding functions. The components may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. Generally, where there are operations shown in the accompanying drawings, these operations may have corresponding components plus functional components with similar numbers.

[0111] The various illustrative logical blocks, modules, and circuits described in conjunction with aspects of the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0112] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. The bus may include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the processing system. The bus may connect various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the user terminal 120 (see Figure 1 ), a user interface (e.g., keyboard, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also connect various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, etc., which are well known in the art and will not be described further. The processor may be implemented with one or more general and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits that can execute software. Those skilled in the art will recognize how to best implement the described functionality for a processing system depending on the specific application and the overall design constraints imposed on the entire system.

[0113] If implemented in software, these functions may be stored on a computer-readable medium or sent on a computer-readable medium as one or more instructions or codes. Software should be broadly interpreted as referring to instructions, data, or any combination thereof, whether it is referred to as software, firmware, middleware, microcode, hardware description language, or other. Computer-readable media include both computer storage media and communication media, and communication media include any media that helps to transfer a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on a machine-readable storage medium. A computer-readable storage medium may be coupled to a processor so that the processor can read information from the storage medium and can write information to the storage medium. Alternatively, the storage medium may be an integral part of the processor. For example, a machine-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium on which instructions separated from a wireless node are stored, all of which may be accessed by a processor through a bus interface. Alternatively or in addition, a machine-readable medium or any part thereof may be integrated into a processor, such as a case where a cache and / or a general register file may be provided. Examples of machine-readable storage media may include, for example, RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. The machine-readable medium may be embodied in a computer program product.

[0114] A software module may include a single instruction or many instructions and may be distributed over several different code segments, between different programs, and across multiple storage media. A computer-readable medium may include multiple software modules. A software module includes instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a sending module and a receiving module. Each software module may reside in a single storage device or be distributed over multiple storage devices. For example, when a triggering event occurs, a software module may be loaded from a hard drive into a RAM. During the execution of a software module, a processor may load certain instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functions of a software module below, it will be understood that the function is implemented by the processor when an instruction from the software module is executed.

[0115] Moreover, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio and microwave are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc Wherein magnetic disks generally reproduce data magnetically, while optical disks reproduce data optically with lasers. Therefore, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). In addition, for other aspects, computer-readable media may include transient computer-readable media (e.g., signals). The above combinations should also be included in the scope of computer-readable media.

[0116] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and / or encoded) thereon, which instructions (e.g., instructions for performing the operations described herein) may be executed by one or more processors to perform the operations described herein.

[0117] In addition, it should be understood that the modules and / or other suitable components for performing the methods and techniques described herein can be downloaded and / or otherwise obtained by the user terminal and / or base station. For example, such a device can be coupled to a server to facilitate the transfer of components for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage component (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk), so that the user terminal and / or base station can obtain various methods when the storage device is coupled or provided to the device. In addition, any other suitable technology for providing the methods and techniques described herein to the device can be utilized.

[0118] It is to be understood that the claims are not limited to the precise configuration and components shown above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. An apparatus for wireless communication by a first user equipment UE, comprising: Memory; as well as One or more processors coupled to the memory, the one or more processors and the memory being configured to: monitoring signaling from at least one of the first UE or the second UE during a DRX cycle associated with a discontinuous reception (DRX) configuration of the second UE; Based on the monitoring, determining whether the first UE and the second UE are within a communication range; as well as Taking one or more actions based on the determination, wherein the one or more actions include: if the signaling is not successfully received, reporting to a network entity that the first UE and the second UE are not within the communication range.

2. The device according to claim 1, wherein: If the energy level associated with the signaling is below a threshold, then the signaling was not successfully received.

3. The device according to claim 1, wherein: monitoring the signaling if the DRX configuration is configured for the at least one of the first UE or the second UE.

4. The device according to claim 1, wherein: The signaling is sent by the second UE during multiple periodic transmission opportunities, and the one or more processors and the memory are also configured to select a frequency for monitoring the signaling, and the signaling is monitored during one or more periodic transmission opportunities among the multiple periodic transmission opportunities according to the selection.

5. The device according to claim 4, wherein: The selection of a frequency to monitor the signaling is based on an energy level associated with receipt of the signaling during one of the plurality of periodic transmission opportunities.

6. The device according to claim 1, wherein: The signaling is sent during a plurality of periodic sending opportunities, and the periodic sending opportunities occur less frequently than the sending opportunities of the synchronization signal blocks SSB or the channel state information CSI-reference signals RS.

7. The device according to claim 1, wherein: The signaling includes less information than SSB or CSI-RS.

8. The device according to claim 1, wherein: The one or more processors and the memory are further configured to: determining resources for sending other signaling, where the other signaling is to be used by the second UE to determine whether the first UE and the second UE are within communication range; as well as If the signaling from the second UE is not successfully received at the first UE, the sending of the other signaling is abandoned.

9. The device according to claim 1, wherein: If the signaling from the second UE is not successfully received at the first UE, the one or more processors and the memory are further configured to: determining resources for sending other signaling; and If the first UE communicates with a third UE, the other signaling is sent, and the other signaling is used by the third UE to determine whether the first UE and the third UE are within the communication range.

10. The device according to claim 1, wherein: The signaling includes a sequence identifying the second UE.

11. A method for wireless communication by a first user equipment UE, comprising: monitoring signaling from at least one of the first UE or the second UE during a DRX cycle associated with a discontinuous reception (DRX) configuration of the second UE; Based on the monitoring, determining whether the first UE and the second UE are within a communication range; as well as Taking one or more actions based on the determination, wherein the one or more actions include: if the signaling is not successfully received, reporting to a network entity that the first UE and the second UE are not within the communication range.

12. The method according to claim 11, wherein: If the energy level associated with the signaling is below a threshold, then the signaling was not successfully received.

13. The method according to claim 11, wherein: The signaling is monitored if the DRX configuration is configured for at least one of the first UE or the second UE.

14. The method according to claim 11, wherein: The signaling is sent by the second UE during a plurality of periodic transmission opportunities, and the method further includes selecting a frequency of monitoring the signaling, wherein the signaling is monitored during one or more periodic transmission opportunities of the plurality of periodic transmission opportunities according to the selection.

15. The method according to claim 14, wherein: The selection of a frequency to monitor the signaling is based on an energy level associated with receipt of the signaling during one of the plurality of periodic transmission opportunities.

16. The method according to claim 11, wherein: The signaling is sent during a plurality of periodic sending opportunities, and the periodic sending opportunities occur less frequently than the sending opportunities of the synchronization signal blocks SSB or the channel state information CSI-reference signals RS.

17. The method according to claim 11, wherein: The signaling includes less information than SSB or CSI-RS.

18. The method according to claim 11, further comprising: determining resources for sending other signaling, where the other signaling is to be used by the second UE to determine whether the first UE and the second UE are within communication range; as well as If the signaling from the second UE is not successfully received at the first UE, the sending of the other signaling is abandoned.

19. The method according to claim 11, wherein: If the signaling from the second UE is not successfully received at the first UE, the method further includes: determining resources for sending other signaling; and If the first UE communicates with a third UE, the other signaling is sent, and the other signaling is used by the third UE to determine whether the first UE and the third UE are within the communication range.

20. The method according to claim 11, wherein: The signaling includes a sequence identifying the second UE.

21. An apparatus for wireless communication by a first user equipment UE, comprising: means for monitoring signaling from at least one of the first UE or the second UE during a DRX cycle associated with a discontinuous reception (DRX) configuration of the second UE; means for determining whether the first UE and the second UE are within communication range based on the monitoring; as well as Means for taking one or more actions based on the determination, wherein the means for taking one or more actions comprises means for reporting to a network entity that the first UE and the second UE are not within the communication range if the signaling is not successfully received.

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